The present invention relates in general to so-called tackless carpet grippers and, more particularly, to a carpet gripper with headless carpet anchoring pins or prongs, the invention further relating to a method of making such a carpet gripper.
Prior art representative of carpet grippers with headed carpet anchoring prongs includes my prior U.S. Pat. No. 3,353,204, issued Nov. 21, 1967. Prior art known to me showing carpet grippers with headless carpet anchoring pins or prongs includes the following patents:
Patentee Patent No. Issue Date ______________________________________ Kent et al 2,752,597 July 3, 1956 Maex 2,806,243 Sept. 17, 1957 Kent et al 2,821,714 Feb. 4, 1958 Maex et al 2,953,788 Sept. 27, 1960 Handy 3,693,212 Sept. 26, 1972 ______________________________________
Headed carpet anchoring prongs perform their function very effectively and provide high resistance to failure due to horizontal carpet tension loads, and also high pullout resistance after failure. Prior headless prongs, on the other hand, have much lower failure resistances due to carpet tension, and much lower pullout resistances after failure.
Despite their superior performance to prior headless carpet anchoring prongs, headed prongs suffer the disadvantage of being much more expensive because of the large amount of metal required for the head. In large volume operations, the metal savings resulting from headless prongs can amount to hundreds of thousands of dollars annually. Headless prongs have the further advantage of being drivable from the top surface of the gripper strip, thus avoiding splintering of the top surface. Such splintering caused by headed pins not only reduces the strength of the wood at the base of the pin where it is most needed for support, but the splinters actually hold the base of the carpet up higher on the pin shaft, where leverage is most detrimental to pin stability.